Fuel composition



United States Patent 3,155,464 FUEL COMPOSITION Richard L. Woodard,Walnut Creek, Califi, assignor to Shell Oil Oompany, New York, N.Y., acorporation of Delaware No Drawing. Filed May 29, 1961, Ser. No. 113,087in Claims. (e1. 44-63} This invention relates to fuel compositions forinternal combustion engines, especially gasoline, and more particularlyto gasoline containing deposit modifiers or ignition control compoundsof phosphorus and/or boron. The invention particularly relates to suchfuel compositions which have improved characteristics with regard tooctane number requirement increase of the engine in which they are used.

During the operation of internal combustion engines, a considerableamount of deposits accumulates on the various areas of the combustionchamber. This accumulation of deposits usually causes, or at leastcontributes to an increase in the octane number requirement of theengine. That is, whereas the clean engine is capable of essentiallyknock-free operation on a fuel of lower octane number, after the enginehas been run for some time and has thus accumulated deposits in thecombustion chamber, it then requires a fuel of higher octane number tomaintain essentially knock-free operation. The character of combustionchamber deposits may vary widely and depends upon a large number ofvariables such as (l) manner in which the engine is run, (2) fuelcomposition, and (3) amount and character of the additives in thegasoline. The first of these three variables is not susceptible tostrict control. The manner in which the engine is run is largelydetermined by the service to which an engine is subjected and thedriving habits of the consumer. Fuel composition from a given refiner isnot subject to wide variations since the fuel composition is governedmainly by octane number demands, blending characteristics of fuelcomponents, and the economics of both these factors. However, both theperformance characteristics of the fuel and the deposit tendencies ofgasoline may be affected to a marked degree by the incorporation ofadditives.

Essentially all commercially available motor gasolines contain additivesof various types. The most common of these are the tetraalkylleadantiknock compounds such as tetraethyllead and tetramethyllead, whichare added in concentrations up to 4 cc. per U.S. gallon in motorgasoline and up to 6 cc. per U.S. gallon in aviation gasoline. Otherorgano-metallic ant-iknock additives which may be used are suchmaterials as cyclopentadienyl nickel nitrosyl, methylcyclopentadienylmanganese tricarbonyl, iron pentacarbonyl, tris(acetylacetonate) iron,nickel Z-ethyl salicylate, bis(n-butyl salicylaldimine) nickel, vanadiumacetylacetonate, ferrocenes and the like. However, because of the risein criticality of ignition control problems such as pre-ignb tion, wildping, and rumble or pounding, in modern automotive engines, bettergasolines today also contain certain ignition control additives. Themost effective of the ignition control additives in use currently, andthose with which the invention is concerned, are compounds of phosphorusand, to a lesser extent, compounds of boron.

Phosphorus compounds which are useful as ignition control additives inleaded gasolines containing halohydrocarbon scavengers are alkarylphosphates or phosphites as in U.S. patent to Yust et al., 2,889,212,issued June 2,

1959, alicyclic phosphates as shown in U.S. patent to Yust et al.,2,765,220, issued October 2, 1956, carbocyclic phosphorus compoundscontaining a direct carbon-tophosphorus bond as in U.S. patent to Yustet al., 2,828,195, issued March 25, 1958, esten'fied thiophosphates andthiophosphites containing at least one alkaryl Patented Nov. 3, 1964 ICCester group as in U.S. patent to Yust et al., 2,843,465, issued July 15,1958, tri-heterocyclic phosphates as in U.S. patent to Yust et al.,2,841,480, issued July 1, 1958, tri(beta-haloaliphatic) phosphites andphosphates as in U.S. patent to Kolka, 2,866,808, issued December 30,1958, dimethyl monophenyl phosphates as in U.S. patent to Orloif et al.,2,911,431, issued November 3, 1959, dimethyl monophenyl phosphates as inU.S. patent to Orloif et al., 2,870,186, issued January 20, 1959, andalkyl phosphates and phosphites.

Among the boron compounds useful as additives for abnormal ignitioncontrol are oleophilic group-substituted heterocyclic compounds of boronand nitrogen as shown in U.S. patent to Scott et al., 2,821,463, issuedJanuary 28, 1958, cyclic esters of boric acid as in U.S. patent toGarner, 2,940,839, issued June 14, 1960, alkyl boronic acids as in U.S.patent to Darling, 2,710,251, issued June 7, 1955, and esters of alkanediols and boronic acids as in U.S. patent to Darling, 2,710,252, issuedJune 7, 1955.

Such ignition control additives do not generally reduce the amount ofcombustion chamber deposits but rather they modify the deposits in sucha manner as to reduce abnormal ignition phenomena, e.g., by lowering theelectrical or thermal conductivity of deposits. Furthermore, suchadditives do not significantly reduce the tendency of the octane numberrequirement of the engine to increase. Additives which either removeformed deposits or serve to prevent the deposition of materials on thevarious areas of the combustion chamber are referred to as octanerequirement reduction agents (abbreviated ORR).

It is therefore an object of the invention to provide an improvedinternal combustion engine fuel composition having reduced tendency toform combustion chamber deposits. It is also an object of the inventionto provide a fuel which will reduce the quantity of combustion chamberdeposits which are laid down in such engines. It is a further object ofthe invention to provide an improved fuel composition which will have areduced octane requirement at engine deposit equilibrium. A stillfurther object of the invention is to provide a new method of reducingthe octane number requirement of engines already containing substantialquantities of combustion chamber deposits. Another object of theinvention is to provide an ORR agent with properties such that it willperform effectively in an internal combustion engine under varyingconditions. Still other objects will become apparent in the descriptionof the invention.

The attainment of these and other objects will be apparent from thedetailed description of the invention, which, broadly stated, is animproved gasoline type hydrocarbon fuel for internal combustion enginescontaining an organo-metallic' antiknock compound, a surface ignitioncontrol additive and a small amount of nitrogen containing heterocycliccompound having at least 5 carbon atoms in the cyclic structure. In amore restricted aspect, it is an improved gasoline composition, havingreduced tendency to cause increased octane number requirement inengines, containing an organo-metallic antiknock compound, a boron orphosphorus ignition control compound, and a small amount of a lactamhaving at least 5 carbon atoms and containing carbon, hydrogen, oxygenand nitrogen.

More specifically, the invention is an improved fuel composition for usein internal combustion engines consisting essentially of a stablegasoline composition containing an octane number-improving amount ofor'ganometallic antiknock compound, a minor amount of an ignitioncontrol phosphorus or boron compound, or a mixture of two or moreignition control compounds, and from 0.05 to 5.0% by weight of agasoline soluble cyclic amide or mixtures of cyclic amides containingonly hydrogen and carbon atoms in addition to the amido-nitrogen 3 andoxygen atoms. These compounds may be represented by the followingstructural formula:

In the foregoing formula, each R can be a hydrogen atom or a lowmolecular weight radical containing from 1 to 4 carbon atomsinclusively, x is an integer from 1 to 2 with the proviso that when xequals 2 one of the Rs must be an alkyl group, the compound having from5 to 14 carbon atoms. These materials can be further described aslactams, that is, as the nitrogen containing heterocyclic compoundformed by the intrarnolecular condensation of an amino carboxylic acidand characterized by the grouping o H II I In a preferred embodiment ofthe invention, x equals 1 and all Rs are hydrogen, i.e., the lactamZ-piperidone is a preferred ORR agent of the invention. The aboveformula will be referred to hereafter as (I).

Specific examples of ORR agents of the invention includefl-methyl-e-caprolactam, i.e.

CHT-CHCH8 and S-butyl-Z-piperidone, i.e.

N CH1 CH (CH2) zCHz-CEE engine having a significant equilibrium octanerequirement increase. It was further noted that the 7 membered lactamcompounds of Formula I were ineffective as ORR agents unless the ringwas substituted with one or more alkyl groups.

The surprising benefits which may be obtained from the use of thelactams of Formula I will be seen and the invention will be more fullyunderstood from the following examples.

Example I A clean Oldsmobile CFR engine was operated on a commercialpremium gasoline fuel containing 3 cc. per gallon (U.S.) oftetraethyl-lead as TEL Motor Mix and 0.3 T (theories) of phosphorus inthe form of tricresyl phosphate. The octane number requirement of theclean engine was about 97 Research octane numbers. The octane numberrequirement of the engine rose in the first 20 hours of operation toabout 99.5, declined slightly to 99 in the next 45 hours and then rosesteadily to an equilibrium octane requirement of about 101 Researchoctane numbers (RON) at the end of the 170 hour period. At this time,0.5% by weight of Z-piperidone was added to the fuel and the operationwas continued for another 31 hours. During this latter period when theengine was operating on the same fuel to which the 2-piperidone had beenadded, the octane number requirement of the engine declined from 101 toa level of 98 at the end of 31 hours of operation. These results show avery dramatic decrease in octane number requirement resulting from theaddition of the Z-piperidone to the fuel containing an ignition controladditive.

The results indicate quite clearly that ONR increase of engines runningon leaded gasolines containing ignition control additives may be reducedto an insignificant and unimportant level by the addition of only smallamounts of the lactams of Formula I. In addition it has been found thatthe beneficial effects of the additive are retained for a significantperiod after the engine is switched to a fuel which does not contain theORR additive.

It is not known whether the action of the lactams of Formula I is ofpurely physical nature or whether some chemical interaction of gasolinecomponents also takes place. If the action of the compounds of Formula Iwere only that of a solvent it would be expected that similar materialshaving the same or higher solubility for lead salts would work as well.

Example II A number of organic compounds having analogous structures orwhich contained the same functional groupings, each having a solubilityfor PbCl of at least the same order of magnitude as the lactam compoundsof the invention were tested in essentially the same manner as in theforegoing examples. The results were as fol- Since lead chloride, whichis formed from the decompo sition of the tetraalkyllead and the ethylenedichloride scavenger, is a major component of combustion chamberdeposits, it is evident that the ORR effect of the lactam compounds inaccordance with the invention is not due to solvent power alone.Furthermore, the octane number requirement reduction properties of theclass of the lactam compounds as defined hereinbefore is thought toresult from an unexpected interaction with the ignition control additivein the gasoline. That is, though neither the lactam compounds of theinvention, nor the ignition control additives exhibit any power toreduce octane number requirement in the absence of the other; however,When both are used in accordance with the invention, they co-act toreduce both octane number requirement and combustion chamber deposits aswell.

In the foregoing example the lactams of Formula I were added into thecombustion chamber by inclusion in small quantities in the fuel. When itis added in this manner, these materials should be present in thegasoline in concentrations of at least 0.05% by weight and preferably atleast 0.1% by weight. Though concentrations as high as 5% by weight areeffective to reduce ONR, concentrations over 1.0% by weight areundesirable because of adverse side effects, among which are thetendencies to form sludge and to plug the piston rings. To obtain themost effective results in a concentration of from about 0.1 to 0.6% byweight is preferred, a range of from about 0.3 to 0.5 being particularlypreferred to obtain both maximum deposits removal and reduction in ONR.

Though addition of the compounds of Formula I to the combustion chamberby means of the gasoline is probably the most convenient method ofutilizing the unique properties of the additive, in still another aspectof the invention it has been found that similar benefits may be obtainedby adding the compound only intermittently, but in much largerconcentrations, into the combustion chamber. Thus, a concentratedsolution of the lactam additive in gasoline when added to the combustionchamber, for example, through the spark plug holes or through the intakevalves of an engine which has been run for an extended time on agasoline containing ignition control additive of boron and phosphorusand which contains equilibrium deposits from such operation, iseffective to reduce octane number requirement therein. When at least 15milliliters are added in the foregoing manner to each of the cylindersof an automobile engine, and the engine is then operated, a considerableportion of the deposits is removed and the octane number requirement ofthe engine is considerably reduced. Most elfective distribution of thelactarn additive and most effective results therefrom are obtained byrapidly accelerating the engine immediately after adding the additiveconcentrate. Moreover, the beneficial effect in ONR reduction isretained for a considerable period, for example, up to 100 hours offurther operation, Without further addition of the additive concentrate.Though the foregoing amount of the additive concentrate may be added allat one time, it is preferable to add it in increments of, say 5-15smaller dosages over a 30-60 minute period. In either case, when thelactam additive is added in the concentrated form, none of the additiveis required in the principal fuel supply.

The concentrated solution of the additive should contain at least 25% byvolume of the lactam additive in order to get significant benefits.However, the concentrate should not contain over about 75% by volume ofthe additive. At higher concentrations the effect of the additive isrelatively low per unit of concentrate added due, in large part, tomaldistribution to the various parts of the combustion chamber.Therefore, a 50/50 mixture of the lactam additive and diluent ispreferred.

As diluent for the ORR additive concentrate any nonviscous readilyburnable organic compound in which the additive is soluble may be used.However, for reasons of both economics and availability, it is preferredto use a hydrocarbon fuel therefor. When gasoline is used as thediluent, it may contain additives such as tetraethyllead and ignitioncontrol compounds; however, these are notrequired. 1 The ORR agents ofFormula I were also found to be effective in multicylinder engines. SeeExample III.

Example III I A 1957 Cadillac engine (8 cylinders) was operated on acommercial premium fuel of the same type as used in The equilibriumoctane requirement of the engine was reduced 1 ON after 37 hours ofoperation on a' similar fuel containing 0.5% byweight piperidone.

The fuel to which the additive is added is preferably a gasoline boilingin the range of about 30 F. to 600 F. and especially preferred is agasoline having a boiling range from about 30 F. to 425 F. andpreferably consisting mainly of hydrocarbons... However, the additivescan also be added to diesel engine fuel comprising hydrocarbons boilingin the range of about 400 F. to 750 F. and to jet engine fuelscomprising hydrocarbons boiling in the range of about 100 F. to 600 F.It will, of course, be recognized by anyone skilled in the art of fuelstechnology that the composition of the gasoline fuel is not at allcritical as regards hydrocarbon type or the use of nonhydrocarbonconstituents such as alkanols and alkyl ethers and the use of othertypes of additives. Thus any practicable stable motor gasoline fuel maybe employed so long as it contains an operable amount of the ignitioncontrol additive, which will usually be from about 0.1 to 2.0 T when theignition control additive is a phosphorus compound, and from about 0.5to 10 T when the ignition control additive is a boron compound.

As applied to the phosphorus ignition control compound, the term theorydesignates the amountrequired to react stoichiometrically with the leadso that all of the lead atoms and all of the phosphorus atoms form Pb(PO As applied to the boron ignition control compound, the term theorydesignates the amount required to react stoichiometrically with the leadso that all of the-lead atoms and all of the boron atoms from Pb (BO Itwill, of course, be recognized that when other organo-metallic antiknockcompounds which contain no lead are used, the term theory refers to thestoichiometric amount of phosphorus or boron which will react with themetal in the organo-metallic antiknock compound to form the analogousmetal phosphates or orthoborates.

Besides the aforementioned ignition control compounds, lead scavengers,and organo-metallic antiknock compounds, the fuel compositions of theinvention can, and ordinarily will, contain other additives, forexample, dyes, oxidation inhibitorssuch asN,N'-ditertiarybutyl-4-methylphenol, metal activators such asN,N'-disalicylal-l,2-propanediamine, and rust inhibitors such aspolymerized linoleic acidsand N,C-disubstituted imidazolines, and thelike. In addition, the fuel compositions of the invention may alsocontain small amounts of various supplemental or co-antiknock compoundswhich are employed to enhance the antiknock action of the primaryantiknock additives. These co-antiknock compounds may be organometallicin nature, such as iron pentacarbonyl, methyl cyclopentadienyl manganesetricarbonyl, and cyclopentadienyl nickel nitrosyl, or they may beprimarily organic in nature, such as tertiary butyl acetate.

The following are illustrative examples of compositions suitable for useaccording to the invention:

Example IV I Gasoline containing tetraethyllead, 1.0 theory ethylenedibromide, 0.3 theory tricresyl phosphate, and 0.5% by weight2-piperidone.

Example V Gasoline containing tetraethyllead, 0.5 theory ethylenedibromide,. 1.0 theory ethylene dichloride, 1.52 theories of his(2-methyl-2,4-pentanediol) meso-borate, 0.18 theory of tricresylphosphate, and 0.25% by weight N-methyl (-s) .caprolactam.

Example VIII Gasoline containing tetraethyllead, 0.3 theory tricresylphosphate, and 0.5% by weight 5-methyl-2-piperidone.

I Example IX Gasoline containing methylcyclopentadienyl manganesetricarbonyl, 0.3 theory tricresyl phosphate, and 0.5% by Weightfi-methyLs-caprolactam.

Example X Gasoline containing tetraethyllead, 0.3 theory tricresylphosphate, 1.0 theory ethylene dibromide, and 0.4% by weight ofN-methyl-Z,S-dimethyl-Z-piperidone.

Example XI Gasoline containing tetraethyllead, 0.5 theory ethylenedibromide, 1.0 theory ethylene dichloride, and 1.0% by weight of N-butyl(e) caprolactam.

Example XII Gasoline containing tetraethyllead, 0.2 theory tris(chloropropyl) thionophosphate, and 0.3% by weightN-methyl--ditertiarybutyl-2-piperidone.

Example XIII Gasoline containing tetraethyllead, 0.5 theory ethylenedibromide, 1.0 theory ethylene dichloride, 0.2 theory tricresylphosphate, and 0.8% by weight 2-piperidone.

Example XIV Gasoline containing tetraethyllead, 0.5 theory ethylenedibromide, 1.0 theory ethylene dichloride, 0.3 theory tri- (chloroethyl)phosphate, and 0.5% by weight of N-propyl (-s) caprolactam.

Example XV Gasoline containing tetraethyllead, 0.5 theory ethylenedibromide, 1.0 theory ethylene dichloride, 0.4 theory cresyl diphenylphosphate, and 0.05% by weight 3,4-dimethyl-2-piperidone.

It is to be understood that the order of mixing the various constituentsof the compositions of the invention in gasoline is immaterial. Forexample, the ORR agent of Formula I may be added to gasoline whichalready contains ignition control and antiknock compounds. Likewise, theORR agent, ignition control compound and an antiknock compound may befirst mixed, stored and handled as a concentrate and added to thegasoline at a later time. A gasoline additive concentrate of this lattertype may also contain halogen scavenger compounds and other additives.Under some circumstances it may be desirable to mix the halogenscavenger and the antiknock compound with the ORR compound of Formula Iin the desired relative proportions and handle or store this mixturewith or without stabilizers, anti-fouling compounds, inhibitors, etc.,as a concentrate for incorporation with the other components of theultimate fuel composition.

I claim as my invention:

1. An improved fuel composition for use in internal combustion enginesconsisting essentially of a stable gasoline boiling between about 30 F.and about 425 F. containing an octane-number-improving amount of anorganometallic antiknock agent, a minor amount of an ignition controldeposit modifying compound selected from the group consisting ofcompounds of phosphorus, boron and mixtures thereof, and an octanerequirement reducing amount of a gasoline soluble heterocyclic compoundcontaining from 5 to 14 carbon atoms and having the structural formula:

wherein R is selected from the group consisting of a hydrogen atom, alow molecular weight alkyl radical con- (J taining from 1 to 4 carbonatoms, x is an integer from 1 to 2 with the proviso that when x equals 2one R is an alkyl group.

2. An improved fuel composition for use in internal combustion enginesconsisting essentially of a stable gasoline boiling between about 30 F.and 425 F. containing an octane number-improving amount of atetraalkyllead antiknock agent, a minor amount of an ignition controladditive selected from the group consisting of compounds of phosphorus,boron, and mixtures thereof, and from 0.05 to 5.0% by weight of gasolinesoluble heterocyclic compound containing from 5 to 14 carbon atoms andhaving the structural formula:

wherein R is selected from the group consisting of a hydrogen atom, alow molecular weight alkyl radical containing from 1 to 4 carbon atoms,x is an integer from 1 to 2 with the proviso that when x equals 2 one Ris an alkyl group.

3. The composition of claim 1 which contains from 0.05 to 1.0% by weightof the heterocyclic compound.

4. The composition of claim 1 in which the heterocyclic compound is,8-methyl-(e)-caprolactam.

5. The composition of claim 1 in which the heterocyclic compound is5-methyl-2-piperidone.

6. The composition of claim 1 in which the organometallic primaryantiknock agent is methylcyclopentadienyl manganese tricarbonyl.

7. The composition of claim 2 in which the organometallic primaryantiknock agent is tetraethyllead.

8. The composition of claim 2 in which the organometallic primaryantiknock agent is tetramethyllead.

9. An improved fuel composition for use in internal combustion enginesconsisting essentially of a stable gasoline boiling between about 30 F.and 425 F. containing an octane number-improving amount of anorgano-metallic primary antiknock agent and from 0.05 to 5.0% by weightof an alkyl-substituted Z-piperidone compound.

10. A new method for reducing combustion chamber deposits and octanenumber requirement of engines containing combustion chamber depositsformed during operation of the engine on gasoline fuel containing anignition control additive selected from the group consisting ofcompounds of phosphorus, boron, and mixtures thereof, which comprisesadding at least 15 milliliters of a gasoline fuel, containing dissolvedtherein from about 25 to about by volume of an alkyl-substituted2-piperidone compound, directly to the combustion chambers of saidengine and operating the engine.

References Cited in the file of this patent UNITED STATES PATENTS1,908,705 Jaeger May 16, 1933 2,784,191 Fischer et a1. Mar. 5, 19572,806,847 Nedwick Sept. 17, 1957 2,806,848 Nedwick Sept. 17, 1957

1. AN IMPROVED FUEL COMPOSITION FOR USE IN INTERNAL COMBUSTION ENGINESCONSISTING ESSENTIALLY OF A STABLE GASOLINE BOILING BETWEEN ABOUT 30*F.AND ABOUT 425*F. CONTAINING AN OCTANE-NUMBER-IMPROVING AMOUNT OF ANORGANOMETALLIC ANTIKNOCK AGENT, A MINOR AMOUNT OF AN IGNITION CONTROLDEPOSIT MODIFYING COMPOUND SELECTED FROM THE GROUP CONSISTING OFCOMPOUNDS OF PHOSPHORUS, BORON AND MIXTURES THEREOF, AND AN OCTANEREQUIREMENT REDUCING AMOUNT OF A GASOLINE SOLUBLE HETEROCYCLIC COMPOUNDCONTAINING FROM 5 TO 14 CARBON ATOMS AND HAVING THE STRUCTURAL FROMULA: